If we check the element VG, we can see that this addin basically runs through and applies a By Element override to each element in the view:

Note: a nice added bonus to the above functionality is that if you open Color Splasher and click “Clear Set”, every Element visibility override in the current view will be removed. Might be handy for QA and model management?

They have also provided a Element GUID tool. It works like the Select by ID tool in Revit, but instead of using the Element ID, it works on the GUID parameter inherent in all Revit elements: